1. Technical Field
This invention relates to a reversing switch, and more particularly to a reversing switch having a wiping function wherein when a bad conductor such as dust is deposited on a contact portion, it is automatically cleared off from the contact portion and the presence of the bad conductor may be eliminated.
2. Prior Art
Generally, the reversing switch is used for the purpose of reversing a direction of current, for example. The switch includes a substantially V-shaped swinging contact plate provided at both ends with a normally open movable contact and a normally closed movable contact, an intermediate supporting member for supporting a normally open contact side of a central bent portion of the swinging contact plate, a swingable knob having a pin at its lower end biased by a spring and adapted to be projected and retracted. When the knob is swung, the pin is slid on an arm portion of the swinging contact plate to thereby reversely incline the swinging contact plate and bring the normally open movable contact into contact with a fixed contact. The swinging contact plate is formed of a relatively hard member such that it is not deformed even when the pin is normally slid thereon.
If there is present a bad conductor such as dust between the movable contact and the fixed contact, the electrical connection between both the contacts are blocked. In the case that the normally open movable contact is switched on and off, an arc is generated to effect the wiping of the bad conductor, thus generating a relatively lesser problem. However, as the generation of the arc cannot be expected at the normally closed contact, it is necessary to swing the swinging contact plate many times to remove the bad conductor, and in the worst case, it is necessary to disassemble the reversing switch for cleaning. Further, in a manufacturing stage, such a reversing switch is necessarily abandoned from the viewpoint of efficiency.
Moreover, even at the normally open contact, it cannot be expected to completely carry out the wiping operation by the arc, and it is therefore required to reliably carry out the wiping operation.